Since Bitcoin has become a dominant cryptocurrency online, would you say that Satoshi had foreseen Bitcoin becoming a major currency today? Any speculations as to what or who were his/her influences in creating Bitcoin?
I guess Satoshi did knew that bitcoin would become popular, but not sure if he had foreseen the extent of bitcoins popularity. Satoshi chose 21 million as the limit because if bitcoin didn't become popular then the number wasn't too high and if it became popular then it wasn't too low.
My choice for the number of coins and distribution schedule was an educated guess. It was a difficult choice, because once the network is going it's locked in and we're stuck with it. I wanted to pick something that would make prices similar to existing currencies, but without knowing the future, that's very hard. I ended up picking something in the middle. If Bitcoin remains a small niche, it'll be worth less per unit than existing currencies. If you imagine it being used for some fraction of world commerce, then there's only going to be 21 million coins for the whole world, so it would be worth much more per unit. Values are 64-bit integers with 8 decimal places, so 1 coin is represented internally as 100000000. There's plenty of granularity if typical prices become small.
https://bitcoinfoundation.org/forum/index.php?/topic/54-my-first-message-to-satoshi/As far why Satoshi created bitcoin:
The root problem with conventional currency is all the trust that's required to make it work. The central bank must be trusted not to debase the currency, but the history of fiat currencies is full of breaches of that trust. Banks must be trusted to hold our money and transfer it electronically, but they lend it out in waves of credit bubbles with barely a fraction in reserve. We have to trust them with our privacy, trust them not to let identity thieves drain our accounts. Their massive overhead costs make micropayments impossible.
There were a few centralized virtual currencies before bitcoin, one of them was DigiCash and then the Bit Gold proposal by Nick Szabo, Satoshi might have got influenced from these.